The overall objective of the proposed research is to elucidate the mechanism of urinary bladder carcinogenesis. The immediate objectives are to obtain evidence to support our working hypotheses: i) that bladder carcinogenesis is enhanced by the specific urinary components which are capable of inducing ODC activity of the carcinogen-initiated bladder epithelial cells, and ii) N-butyl-N(3-carboxypropyl) nitrosamine (BCPN) is indeed the proximate carcinogenic metabolite of N-butyl-N-(4hydroxybutyl) nitrosamine (BHBN) but requires urine (or urinary tumor-enhancing factors) for the expression of its carcinogenecity. To prove these hypotheses, the following 2 specific aims are proposed: 1. to determine if the inhibition of polyamine biosynthesis by Alpha-difluoromethylornithine (DFMO), an irreversible inhibitor or ornithine decarboxylase, can suppress the urinary bladder carcinogenesis by N-methyl-N-nitrosourea. If DFMO suppresses bladder tumorigenesis, an attempt will be made to restore carcinogenecity by adding putrescine tumorigenesis, an attempt will be made to restore carcinogenecity by adding putrescine to the same experimental system. This is to test if carcinogenesis is dependent upon adequate pools of intracellular polyamines. 2. to assess the role of normal urine in the BCPN-initated urinary bladder carcinogenesis in rats. Both studies will be conducted using the heterotopically transplanted urinary bladder system developed in our laboratory. For aim #2, a short term assay (agglutinability of bladder epithelial cells by concanavalin A described by Kakizoe) will be conducted before a long-term carcinogenesis assay is conducted.